The Doctor makes an unexpected return trip to the planet Konzomia, this time with Sarah Jane Smith. The traumas of his previous visit, with Jo Grant, are apparently long forgotten. 

Except that they are not...

Can a long-defeated danger be rearing up again? And will the plight of a young British soldier, retreating to Dunkirk in 1940, be the catalyst for the unravelling of history? 

The Doctor, Sarah and the Brigadier must embark upon a mission of mercy, with Jo Grant at its very heart.